A plurality of methods are previously known for making a cardboard barrel liquid-tight. One method is to provide the inner surface of the wall and bottom plate of the barrel with a plastic coating before joining the bottom plate to the wall portion. The bottom plate is hereafter mechanically joined to the cylindrical wall portion. This solutions suffers from the disadvantage of an unreliable liquid-tightness at the joint between the bottom plate and the wall because if the barrel during transport is subjected to bumps, a slit may be formed in the joint through which liquid is able to flow out of the barrel. The strength of the joint can be improved by welding the coatings the each other at the joint but because the thin plastic film is easily torn in connection with the deformation of the joint, is this sealing method neither very reliable. In this connection it is also to be noted that the upper and lower edge of the barrel are in general mostly subjected to bumps.
In addition to the above described barrel, barrels are known inside which a plastic bag is arranged which is secured to the barrel at its mouth only. The liquid-tightness of such a barrel in general remains satisfactory inspite of bumps because the deformations of the barrel do not directly affect the bag. However, barrels provided with a loose inner bag suffer from a plurality of disadvantages, wherefore they are not very commonly used. They are particularly difficult to fill and empty.